“Change is the only
constant in life.” This is an age old saying and it is so true! As we
look back in
time that has gone by, the evolution in technologies that impact
our life is amazing and for the new generations it is difficult to imagine the
path traversed by elders. For example, look at the development in telephony and
communications; there was a time when, to get a telephone we had to make a
lengthy application with documents plus a hefty deposit and then wait for 3
years to get a telephone. For dialing national or international numbers one had
to book a call and experience endless wait to be connected for a 3 minute call.
Those who did not have telephone connections had to visit a post office to call
relatives in other cities, book a call and wait for their turn until the
operator tried to connect them for a call that they had to pre-declare the
duration as 3 minutes or 6 minutes. Mobiles have transformed life and we have instant
voice and video communication capabilities 24X7 with multiple phones in our
pockets. The mobile is perhaps the most impactful technology experienced by us
in life so far. In a somewhat similar manner, printing technologies have
evolved over hundreds of years to bring changes enabling perfection and
colourful meaning to all printed products. A technology that began with carving
stone blocks, apply colours and transferring images, evolved to using wooden
blocks, metal type sets, letterpress printing, screen Printing to offset
printing, a technology that was widely adopted and spread across the world as
the most preferred print process. Also evolved flexographic and rotogravure
printing. All these technologies had a costly pre-press and make-ready process as
also the cost of artworks, plates, print cylinders, etc.
The 1970s saw the beginning of an era that
would continue to impact the print industry in a totally different tangent, the
digital printing! The technology enabled printing with a command from a
computer with press of a button without much of processes that were needed in conventional
printing. It is so much like the changes in mobile phone technology coming
about. By 1993 the digital printing technology developed such that the first commercial
digital printing press named “Indigo” was produced by Benny Landa in his
company with the same name. This transformed the printing world; one could now
print personalized
short run jobs straight from computer. In 2000-2001, the company Indigo was
acquired by Hewlett Packard (HP) and at the time of acquisition Landa had said,
“Our
vision has always been to lead the printing industry into the digital era and
to see Indigo technology pervade the commercial market. Now, a part of HP, that
goal is in sight." Rightly so, the market of digital printing has been
registering robust growth. Digital printing technology has been developed by
various press manufacturers and is being widely adopted with innovative
indulgence. Label manufacturing is an
integral part of print and has also been witnessing growth both in terms of
total market as well as in Digital printing of labels. The global market
for label printing has been growing steadily in recent times, valuing at $36.98
billion in 2017. As per Smithers Pira the total market of labels is likely to cross 49.9
Billion USD by 2024. According to Finat; 2017 was the first year that, with
nearly 300 digital press installations, the volume of newly added digital label
presses surpassed that of new conventional label press installed volumes.
While
label printers in the western world have been early investors in digital label
printing presses yet the Indian printers have been skeptical about the need for
this investment in the Indian label production scenario. For this reason, until
about 2015 most of the established label printers adopted the wait and watch
stance toward digital printing of labels. However, in recent times we see the
interest and investment towards this technology growing slowly and steadily,
though the rate of growth in digitally printed labels is still small.
Increasing number of printers have been seen studying the digital label
printing technologies at labelexpos. Advantages of digital printing include
speed, flexibility and low prepress costs, not requiring expensive plates shorter
times to make ready. It is especially useful when printing variable data
(numbering, bar- or QR codes, content variations, etc.).
The
different types of technologies available leave the printers in a confusion as
to what is the most appropriate technology that they should invest in. Unlike
other conventional printing processes evolution of digital printing has moved
into different technical ways of achieving the same goal which is computer to
print.
Largely
available technologies offered by various manufacturers of digital equipment
are as follows;
1.
Dry toner based
2.
Liquid toner based
3.
Inkjet
4.
UV Inkjet
While looking at the selection of
digital print process one also needs to decide the finishing of the labels
whether they wish to do this inline or offline. Every different short run job
maybe of varying shape requiring frequent stops and change of cutting dies.
This substantially reduces press running time and impacts profitability
adversely. In such a case it is advisable to finish the labels offline, one
offline equipment can free up printing time of multiple presses. Laser die
cutting is another option whereby it can handle multiple and frequent job
changes without the need for additional dies and machine stoppages, but this
calls for a much higher investment in the finishing equipment. Additionally, one needs to decide with
digital, what dpi resolution to go for; does the work need a white ink in one
of the printing heads; does the press have an extended color gamut. Press
running speeds of all the digital label press technologies vary quite
considerably. The printing speed with many short-run job changes is also an
important factor for consideration.
Dry Toner based process:
 |
| Chester Carlson inventor of Xerography |
This process is an evolution of the
earliest photocopying process known as Xerography invented by Chester Carlson founder of Xerox and converted as Laser printer by Gary Keith Starkweather in 1970s which transformed to digital printing with laser printers also called electrostatic
digital printing as we have seen in our offices. In a laser printer a laser
beam runs over an electrically charged drum preparing an electrical image
carrying charged areas. The drum is a cylinder coated with a material
that becomes conductive when exposed to light or laser beam. Areas that are not
exposed have a high resistance which allows these areas to hold the
electrostatic charge necessary for the process. The image then collects the toner
and transfers the image to a paper or substrate that is then heated to fuse the
image on to it. In traditional xerography the image is formed by reflecting
light off an existing document onto the exposed drum which then picks up the
toner and transfers the image. Dry toners consist of pigments embedded inside
polymer beads. The fusing phase of the electrophotographic process melts the
polymer beads to the surface of the paper. These can print on both coated and
noncoated papers. Image quality is a complex issue, determined by a combination
of hardware, software, consumables and processes. Dry toner is not absorbed by
the substrate, it always achieves an optimal optical density as all the
ink transferred is adhering on surface. The particle size of the toner has been
reduced over the years to achieve fine print results and most equipment are
offering prints of 1200 DPI for solids and blends with good color depth and
subtle contrasts, ideal to reproduce vibrant images.
Major
brands offering dry toner based digital label presses are Xeikon and Konica
Minolta.
Liquid Toner based process
Liquid toners also use pigments in polymer beads, but they are dispersed in oil that evaporates during fusing process. Liquid toners are used in digital presses that are typically used for commercial printing on a wide range of coated papers. Benny Landa an Israeli inventor
mentioned above, having to his credit 800 patents produced the first Indigo digital
printing press in the early 1990s using liquid toners in a process that was
called liquid electrophotography or LEP in his company established in 1977. Landa
came to be known as the father of digital printing. The liquid toner used by HP
came to be known as ElectroInk, that combines the advantages of electronic
printing with the qualities of liquid ink. ElectroInk contains charged
pigmented particles in a liquid carrier. The image is created with
electrophotographic process on the drum directly from digital data, avoiding
the use of any analogue intermediate media. It starts with digitally created
pages or print elements containing text, layouts or images. HP Indigo uses a
blanket in between to transfer ink from the drum to media. The blanket is
heated, melting and blending the ElectroInk particles into a smooth film. This
produces an image that is completely defined on the blanket and transferred to
the substrate by direct contact. For this reason, it is also referred to as offset
digital printing.
Major brand using liquid toner based
digital printing process: HP
Inkjet
Printing
Inkjet printing is the oldest of
technologies in non-contact printing evolving into digital colour printing commercially.
Existing together there are two main inkjet technologies i.e. Continuous Inkjet
(CIJ) and drop-on-demand (DOD). The CIJ method has been in use for ages in
which a high-pressure pump directs liquid ink from a reservoir through a gun body
and a microscopic nozzle, creating a continuous stream of ink droplets. These
droplets are subjected to a varying electrostatic field and then these charged
droplets pass through another electrostatic field to deflect them and form
characters. The process can be understood by the image reproduced from
Wikipedia. The Drop-on-demand (DOD) is divided into thermal DOD and
piezoelectric DOD. Most commercial printers use the DOD to print. The large
format ones use solvent or water-based inks depending on the equipment and the
product. The inks used in digital inkjet label printing presses are water based
and formulated with either dyes or pigments. Aqueous inks provide the broadest color gamut and most vivid colors. The water-based inks are inexpensive and
may ultimately spell out as the lowest cost print, but some substrates may
require specialized coatings as there is an imperative need for the ink droplet
to sink straight in and not to smudge or smear. With growing volumes, increased
environmental and consumer friendly nature of inks the coated stock prices are
likely to become largely affordable making this technology to watch as wider
acceptance is envisaged. Such inkjet printers can achieve high resolution of
1600 DPI. Since the start of a new millennium another water-based inkjet
technology called Memjet has been evolving. Memjet is used in
high speed, full colour printers to give a high-quality print at a very low
cost. It uses a fixed print head unlike conventional inkjet printers where the
cartridges or head moves back and forth during printing. The Memjet print head
is fixed and is of the width of the material it’s printing on enabling edge to
edge printing. This way it’s only the material that moves underneath the head
as it’s printed.
Major brands using water based digital inkjet printing:
Trojan from Astronova, Afina, Colordyne
UV
Inkjet Printing
UV inkjet Digital printing is an
extension of the inkjet printing that uses ultra-violet light to dry or cure
ink. The inks
consist mainly of acrylic monomers together with a photo initiator and
after printing when exposed to strong UV lamps or in case of specially
formulated inks to LED-UV light, the ink is cured by crosslinking. The ink due
to this chemical reaction becomes instantly dried leading to increased printing
speeds. The curing process with high power UV exposure for short periods of
time (microseconds) allows printing on thermally sensitive substrates like BOPP
and PE. Since the ink sits on top of the substrates and neither is dried by
evaporation nor by absorption resulting a robust image on a wide range of
uncoated substrates. It is the fastest growing sector of digital
inkjet printing and more sustainable than conventional printing.
Major
brand using digital UV inkjet printing: Canon, Domino, Durst, Epson, Screen,
Xeikon
 |
| Short run labels with variable data |
Selecting digital printing equipment
for label printing is a complex task depending on the printer’s customer portfolio.
It varies on many parameters, like the equipment price, ink price, media cost, media
to be printed, consumables cost, speed of machine, resolution required, space
and finishing required. Time is not far when printers will invest in multiple technologies
to attain the best of each process and to service a wide array of customers. However
to start with the print on demand feature is so very attractive and for short
runs it seems to be becoming an absolute necessary at least in case of
established printers whose large investments in high end flexo or combination
presses gets held up doing shorter runs and taking away valuable production
time. Since short run demands from brand owners continue to swell along with
need for variable data, it becomes necessary to opt for an offline finishing
equipment which does not slow down their printing capabilities.
 |
| Hybrid digital-flexo label press |
Most of the leading label press
manufacturers have started offering Hybrid machines with combination of Digital
and flexo printing capabilities along with decorating and finishing inline. It
is not a simple decision to opt for the hybrids. As mentioned earlier here, it
all depends on the portfolio and requirements of individual label printers. It
is interesting to note that all hybrid presses with digital capabilities
displayed at Labelexpo Europe in September 2019 were fitted with UV inkjet digital
presses. Leading press manufacturer who are offering Hybrids of flexo, digital
and inline finishing include Gallus, Omet, Mark Andy, Nilpeter and MPS. With
environmental concerns, migration of inks and other food or Pharma safety needs,
non-waterbased inkjet systems may see more development in future. As of now due
to the speed and versatility offered by UV Inkjet coupled with the ability to
add additional white and other colours, UV inkjet is the predominantly used
technology however investment is high. Therefore, selection of the best suited
technology for digital in labels must be as per individual printer’s need and
that of their diverse customer mix. It is a competitive time and cost of
equipment, cost of consumables and the nature of output is very important to ponder
over before finally selecting the first entry into digital.
Written
by Harveer Sahni Chairman Weldon Celloplast Limited New Delhi November 2019
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